204 The Masterbuilder - December 2012 • www.masterbuilder.co.in

Coal Ash – An Alternative Material for Green Infrastructure

Bharathi Ganesh1, Dr. H. Sharada Bai21Associate Professor, Dept. of Civil Engineering, Global Academy of Technology, Bangalore2Professor, Dept. of Civil Engineering, UVCE, Bangalore

In spite of the global economic slowdown, India is still the 3rd fastest growing major economy in the world. This booming economy has kick started all industry sectors including the construction & infrastructure industry, which demands for additional 1,08,000 MW power generation to meet the growing economy needs[[V.M. Malhotra,2011]]. Coal will be the main source of energy for the production as it is one of the cheapest sources of fuel, resulting in is generation of huge amount of coal ash. Development of nation through proper infrastructures and managing resources, making construction sustainable, catering to the vast demand in materials requirement for construction due to fast growing infrastructure demand , is a challenge and is the need of the hour[Bharathi Ganesh et.al.Aug.2011].

At a time when so much of our natural resources are depleting we need to be resilient and think of alternative solutions that meet many objectives at the same time. Greening the infrastructure with sustainable alternative materials for construction is one solution.

Huge volume of Coal Ash, a waste product from thermal power stations, generated, if used efficiently, effectively in various constructions encourage the large scale utilization of industrial waste, facilitating human habitation, replacing fast depleting natural resource, so as to contribute to sustainable construction[Bharathi Ganesh et.al.Aug.2011] and also helps in conserving the precious top soil required for growing food contributing to environmental and ecological benefits.

The change in the growth of cities from urban form chosen in the early part of the 20th century, of sprawl to compact cities

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has lead to different carbon related consequences. We are impelled to view urban development, housing infrastructure and transport requirements as crucial determinants of future CO2 emissions.

It is high time now and we are under pressure to reduce CO2 emissions, and also to push for a stronger growing economy in the race towards achieving 2nd largest economy in the world. India is pursuing the goal of a reduction of at least 20 per cent in carbon emission intensity by 2020 (over 2005 levels). It has the opportunity not merely to reduce carbon intensity, but to improve the quality of life for citizens through greening the infrastructure.[Teinventing the City,2010].

Greening the infrastructure can be mainly accomplished by through the practice of creating structures using materials / processes that are environmentally responsible and resource -efficient in every way possible, through the successful implementation of improved technologies (materials / methodology) that will reduce CO2 emissions and it is possible to reduce global warming.

The paper on similar lines was presented by the Author in ‘Conference INWES 2012’ 12th-13th October 2012, at New Delhi.

Different forms of coal ash such as Fly Ash, Bottom Ash and Pond Ash have proved as sustainable materials for various constructions. The coal ash conform its suitability in con-struction in many ways, in the manufacturing of cement, as an alternative material in construction as cementitious content, as fine aggregate in mortar, concrete and also in highway, geotechnical applications.

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While rapid infrastructure build-up is traditionally been carbon intensive, the challenge is to build infrastructure with a smaller carbon footprint,

without compromising poverty alleviation and energy security. As India is in the early stages of infrastructure development, the choices now would determine its future. Renewable energy has long been recognized for its enormous potential in meeting the energy needs of India in a carbon-smart way [The Financial Express,2012]. The solutions of using a industrial byproducts in construction field can be most useful for low carbon emission and sustainable development, apart from creating employment opportunities at all stages of the value chain.

What is Green Infrastructure ?

Green infrastructure is a concept originated in the United States in the mid-1990s that highlights the importance of the natural environment in decisions about land-use planning. In particular there is an emphasis on the “life support” functions provided by a network of natural ecosystems, with an emphasis on interconnectivity to support long-term sustainability [Wikipedia, weblink].

Green Infrastructure is the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building’s life-cycle from sighting to design, selection of materials, construction, operation, maintenance, renovation and deconstruction.

The green infrastructure practice expands and complements the classical building design concerns of economy, utility, durability and comfort and is known as a sustainable or high performance infrastructure.

Green Infrastructure is needed for Ultimate benefits

- Protecting health of end user- Using energy, water, and other resources more efficiently- Reducing the overall impact to the environment.- Improving overall productivity- The benefits of Green infrastructure.

Environmental benefits

- Enhance and protect biodiversity and ecosystems - Improve air and water quality - Reduce waste streams - Conserve and restore natural resources

Economic benefits

- Reduce operating costs - Create, expand, and shape markets for green product

and services - Improve occupant productivity

- Optimize life-cycle economic performance

Social benefits

- Enhance occupant comfort and health - Heighten aesthetic qualities - Minimize strain on local infrastructure

Urban infrastructures are the source of close to 80 % of carbon dioxide emissions, and depending on how we develop and manage it, making it either a force of primary source of ecological rejuvenation or an environmental destruction. Our cities play a vital role in the quest to achieve global ecological sustainability. They are the largest contributors to greenhouse gases and climate change [The Hindu Editorial,2010].

In this context, data from just three countries with high per capita incomes but different emission rates make it evident that development need not involve high carbon pollution. While per capita carbon dioxide emissions for 2006 stood at 19.5 tonnes in the United States, they were 9.1 tonnes in the United Kingdom and 6.4 tonnes in France [The Hindu Editorial,2010].

The urban development, housing infrastructure and transport facility which are crucial determinants of future emissions, are to be directed towards low to zero carbon emissions through lot of efforts during planning, construction and maintenance of urban infrastructure[Ernst Worrell, et. al. 2009].

The cement industry contributes about 5% to global anthropogenic CO2 emissions, making the cement industry an important sector for CO2 contributions. Overall, the top 10 cement-producing countries in 1994 accounted for 63% of global carbon emissions from cement production. One of the dioxide (CO2) emission mitigation options include the energy efficiency improvement such as encouraged use of alternative materials in the manufacturing of cement, which produces less CO2[Ernst Worrell, et. al. 2009].

The emission of CO2 grew 5.9% in 2010 to reach 9.1 GtC (33.5Gt CO2), overcoming a 1.4% decrease in CO2 emissions

YearCement

Productionbillion tonnes

Total C02 Emissions,

billion tonnes

C02 Contribution by cement industry, %

1995 1.4 21.6 7

2008(millions of

tonnes)2.8 36.5 7.7

Developed Countries

1985 2003 2020 (Expected)

Table1: Details of CO2 emissions from Developed and Developing Countries

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in 2009. Including land-use change and deforestation, in 2010 emissions reached 10.0 GtC (36.8 Gt CO2) [V.M. Malhotra,2011].

Coal as Energy Source

Coal was the key energy source which has provided amenities including electricity, new materials (steel, plastics, cement and fertilizers), fast transportation, and advanced communications and contributes to the industrial revolution, coal combustion have been identified as a primary culprit in increasing atmo-spheric CO2 concentrations, strongly affecting the world’s climate[Coal Initiative Reports, 2008].

Coal Facts [ G.K.Pandey 2006]

- Seventy one % of electricity production is based on coal in the country.

- 83 coal based thermal power plants with total generation capacity of 62880.9 MW (as on July, 2003) exist.

- There are 27 gas/naphtha based power plants with total generation capacity of 11299.6 MW (as on July, 2003)

- More than 240 million tonnes of coal with ash content 35-45% is consumed annually by the Thermal Power Plants.

- Nearly 100 million tonnes per annum coal ash is generated. When pulverized coal is burnt in a dry, bottom boiler, about 80 percent of the unburnt material or ash is entrained in the flue gas and is captured and recovered as fly ash. The remaining 20 percent of the ash is dry bottom ash, a dark gray, granular, porous, material that is collected in a water-filled hopper at the bottom of the furnace [Bharathi Ganesh et.al.Oct.2011].

- More than 25,000 hectares of land has been occupied for conventional disposal of ash.

Environmental Issues from Coal Based Power Generation [G.K.Pandey 2006]

- Air Pollution - High particulate matter emission levels due to burning of inferior grade coal which leads to generation of large quantity of flyash. Emissions of SO2, NOx & Green house gas (CO2) are also matter of concern.

- Water Pollution - Mainly caused by the effluent discharge from ash ponds, condenser cooling /cooling tower, DM plant and Boiler blow down.

- Noise Pollution - High noise levels due to release of high pressure steam and running of fans and motors

- Land Degradation - About 100 million tonnes of fly ash is generated by use of coal far energy production. The disposal of such large quantity of fly ash has occupied thousands hectares of land which includes agricultural and forest land too.

- Pollution - High particulate matter emission levels due to burning of inferior grade coal which leads to generation of large quantity of fly ash.

Pollutions from coal based power plant (G.K.Pandey2006) – The details of pollutant emission from coal based thermal power stations is as given in table 2

Pollutants Emissions (in tones/day)

CO2 424650

Particulate Matter 4374

SO2 3311

NOx 4966

Table 2 – Emission of Pollutants from Coal Based Thermal Power Stations

Environmental and Ecological Issues

More than 630 million M3 water is required for disposal of coal ash as in slurry form (bottom ash) per annum. The major constituents of Coal Combustion Residues (CCRs) consist of silica, alumina and iron oxides (^87%). One of the major concerns with coal disposal is the leaching of heavy metals to surface and underground water source, which may contaminate the ground water quality nearby the ash disposal area. But the ultimate impact of each trace element will depend upon its state in CCRs and toxicity, mobility and availability in the ecosystem [Vimal Kumar et. al. 2005]

Figure 1 – Environment and Ecological Issues of Fly Ash

Suitability of Coal Ash

Test results of detailed study on [physical, chemical, morphological] properties of coal ash (Fly Ash / Coal Ash) indicate that ash mixtures compare favorably with conventional materials used for constructions as per relevant code of practice. Fly Ash with its properties such as Fineness, Specific Gravity, Pozzolanic Activity (Chemical Composition and Mineralogy), Loss on Ignition, Moisture Content, Workability, Time of Setting, Bleeding, Pumpability, Strength Development, Heat of Hydration, Permeability, Resistance to Freeze-Thaw, Sulfate Resistance, Alkali-Silica Reactivity, proved its suitability in various fields of constructions. Hence coal ash helps to overcome the shortage of natural raw materials and reduces the CO2 release to atmosphere, contributing to sustainable construction.

Coal Ash Applications in Engineering Field

Exploring the strategies for addressing greenhouse effect

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and to reduce CO2 emissions from coal based thermal Power Plant has lead to several field of applications. Sustainable Coal Ash Applications are as listed here

- Fly Ash in Blended Cement, as Cementitious Content and in concrete

- Fly Ash / Pond Ash for roads, embankment works - Fly Ash / Pond Ash for Geotechnical Applications- Fly Ash in Paints- Fly Ash / Pond Ash as Building Material - Coal Ash (Pond Ash) in Concrete as Fine Aggregate

Fly Ash in Blended Cement, Cementitious Content and in Concrete

The quality of Fly Ash (Physical and chemical properties) is governed by the specifications of IS 3812 – PartI-2003, testing requirements of IS1727-1967, reaffirmed in 1989. High fineness, low carbon content and good reactivity are the essence of good fly ash. The amorphous state of fly ash particles greatly contribute to pozolanic action between cement and Fly Ash. The spherical shape of Fly Ash improves flowability and reduces water demand [M.S. Shetty 2005].

Manufacturing of Blended Cements is in vogue with complementary pozzolanic and cementitious materials like fly ash up to 30%, as an alternative which make cement environment friendly, cost-effective, and durable.

Utilization of fly Ash in Blended Cement / Concrete / Mortar has wide range of applications in R.C.C. works, plastering, underground structures, dams, heavy machinery foundations, marine structures and hydropower stations.

Concrete with fly ash saves virgin material and energy, hence can be called as green concrete. Concrete with 50% to 60% fly ash incorporated in it is known as High Volume Fly Ash[M.S. Shetty 2005]. Because the concrete is more durable, it means that there is less concrete debris created over time, which will add to the savings of energy, landfill space and virgin materials. A ton of Fly Ash taken out of the waste stream will conserve enough landfill space and reduce carbon dioxide emissions equal to two months of emissions by a car [The Green Choice-Web Link].

Benefits of addition of Fly Ash in Cement [FlyAsh put Concrete_weblink]

- Fly Ash in Cement lower heat of hydration when used in

Concrete and mortar.- Reduced permeability (Improved water tightness) - Improved Corrosion resistance - Increased compressive Strength

Benefits of addition of Fly Ash in Concrete [FlyAsh put Concrete_weblink]

- Increased (later) workability and compressive strength- Reduced heat of hydration - No leaching of calcium hydroxide crystals on to the

surface - Increased durability - Reduced sulfate attack, Permeability, Bleeding &

segregation and hence reduced drying shrinkage and low chloride Ion penetration

- when used as a cement replacement it reduces total alkali content by reducing the portland cement.

Pond Ash as Fine Aggregate in Concrete - The characterization of Coarser Ash - Pond Ash conducted to use it as fine aggregate, though totally not very satisfactory, confirm its suitability in concrete as fine aggregate [Ranganath R.V.et. al. 1994] A lot of research has been carried out for the effective utilization of flyash like its use in construction industry etc, very little literature is available on pond ash utilization particularly its use as a constituent material for concrete in construction industry. Hence detailed investigations using pond ash as fine aggregate in concrete is essential to develop the knowledge and experience for proper design and execution of the concrete constructions.

Figure 2 – Fly Ash in Road, Embankment and Geotechnical Applications

Figure 3 – Application of Fly Ash in Construction

Fly Ash / Pond Ash for roads, embankment works

One of the areas identified for its bulk utilisation of coal ash is in construction of roads and embankments. Out of this total utilisation, about 22 per cent amounting to 7.75 million tonnes, was used in the area of roads and embankments in the year 2006 [Sudhir K Shrma et. al 2006].

While testing ash, intending to use it as materials in embank-ment constructions, emphasis is given to the determination of their mechanical characteristics, including compaction, permeability, strength, stiffness and compressibility [PANDIAN N. S. 2004]. Test results indicate that ash mixtures compare favorably with conventional granular materials and found that the maximum dry density and the OMC -

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optimum moisture content for the sample considered for the research, typically ranged from 11.9 to 18.7 kN/m3 and from 13 to 32%, respectively”[Bumjoo Kim]. The standard Proctor maximum densities varied between 11.6 kN/m3 and 18.4 kN/m3. The OMC showed that, at low stress levels, the compressibility of bottom ash was comparable to natural granular soils placed at the same relative density.

Fly Ash for road embankment [Amarnath M.S, 2007].

- Fly Ash is ideally suited as backfill material for urban/ industrial areas and areas with weak sub soils. Provides greater stability because of its higher shear strength

- Is incorporated with design similar to that for earth embankments

- Is used as intermediate soil layer for ease of construction and to provide confinement

- Demands for soil cover to the side slopes for reducing slope erosion.

- Allows compaction under inclement weather conditions- Leads to 15 to 20 per cent savings in construction cost

depending on lead distance

Fly ash for road constructions, stabilised soil subgrade & sub-base/base courses[Amarnath M.S, 2007].

- Mixing with soil reduces plasticity characteristics of subgrade

- Addition of small percentage of lime or cement greatly improves strength

- Leaching of lime is inhibited and durability improves due to addition of fly ash

- Pond ash & bottom ash can also be stabilised - Lime-fly ash mixture is better alternative to moorum for

construction of WBM / WMM

Construction of semi-rigid/ rigid pavements [Amarnath M.S, 2007].

- Lime-fly ash concrete- Dry lean cement fly ash concrete- Roller compacted concrete- Fly ash admixed concrete pavements- Lime-fly ash bound macadam- Precast block paving- High performance concrete

IRC Guidelines / Specifications [Amarnath M.S, 2007].

Guidelines available on pavement construction

- IRC 60 ‘Tentative guidelines for use of lime fly ash concrete as pavement base or sub-base’

- IRC 68 ‘Tentative guidelines on cement fly ash concrete for rigid pavement construction’

- IRC 74 ‘Tentative guidelines for lean cement concrete and lean cement fly ash concrete as a pavement base or sub-base’

- IRC 88 ‘Recommended practice for lime fly ash stabilised soil as base or sub-base in pavement construction’

Specifications – Various Codes for different applications [Amarnath M.S, 2007]

- Published by Indian Roads Congress (SP- 58:2001), includes design aspects also Handling and construction

- Loose layer thickness of 400 mm can be adopted if vibratory rollers are used

- Moisture content - OMC + 2 per cent- Use of vibratory rollers advocated- Minimum dry density to be achieved - 95 per cent of

modified Proctor density- Ash layer and side soil cover to be constructed

simultaneously - IS 456 – 2000 recommends addition of Fly Ash (GGBS,

Silica Fumes, Rice Husk Ash) to be used as as Mineral admixture (as cementitious material) in Concrete and Constructions. [Cl:5.2.1.1., pp13]

Fly Ash in Paints

Paints can also be developed using CCRs for protection of metallic and non-metallic structures and generally for the protection of corrosive environment. CCRs were used (30%) as extender due to its chemical inertness, abrasion resistance, less oil absorption and low specific gravity [www.c-farm.org]. The coal ash in paints showed resistance to water, acid, alkalis, organic solvents and have improved abrasion resistance. Fine particles of coal ash were used for removal of dye under acidic condition at low temperature.

Coal Ash for Building Material

Building materials like bricks, blocks, paints, timber substitute products, etc., with or without combination with lime is also another important area in which 35–50% of fly ash can be utilized without compromising the quality. BMTPC has continued its efforts to develop and promote environment-friendly, energy-efficient & cost effective building materials (Fig.3&4), manufacturing technologies and

Figure 4. Application of Coal Ash in Concrete and other Products in Constructions

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disaster resistant construction practices, an Innovative options which can contribute to cost reduction, and at the same time offer solutions which are durable, functional, acceptable and also aesthetically pleasing, incorporating Fly ash in its products[User Manual, BMTPC 2012].

Coal Ash in Geotechnical Applications

The grain size distribution of coal ash reveals that bottom ashes are coarser particles consisting predominantly of sand-size fraction with some silt-size fraction classifying coal ash as sandy silt to silty sand [Leonards G. A. 1982]. They are poorly graded with coefficient of curvature ranging between 0.61 and 3.70. The reported friction angles varied in a wide range from 35 to 55°, depending on the density. [Pandian N 2004]. The coefficient of uniformity is in the range of 1.59–14.0, the specific gravity generally lies between 1.46 and 2.66 .[Pandian N 1998]. The specific gravity is lower leading to lower unit weights resulting in lower earth pressures.

Index properties are extensively used in geotechnical engineering practices. Among them, liquid limit is an important physical property for use in classification. Coal ashes have liquid limit water content ranging from 22 to 64% for pond ashes. The specific surface obtained ranges between (89 to 530) m2/kg using Blaines Air Permeability method[Pandian N 2004].

Chemical Properties

The detailed study on various investigations carried out on Indian coal ashes show .[Pandian N 2004].the silica content of pond ashes is from (37 and 75)% the alumina content ranges from (11 and 53) % and calcium oxide is in the range of (0.2 to 0.6) % for pond ashes. It is found that all the Indian coal ashes satisfy the chemical requirements for use as a pozzolana according to ASTM classification. Range of chemical composition of Indian coal ashes .[Pandian N 2004] and soils is as given below and is comparable with soil (Table 4).

Applications

The detailed investigations carried out on fly/pond ash show that it has good potential for use in geotechnical

applications. Its low specific gravity, freely draining nature, ease of compaction, insensitiveness to changes in moisture content, good frictional properties, etc. can be gainfully exploited in the construction of embankments, roads, reclamation of low-lying areas, fill behind retaining structures, etc. It can be effectively used for

- Better backfill material for reinforced embankments - Polymeric reinforcing materials – geogrids, friction ties,

geotextiles construction sequence being similar to that of reinforced earth structures

Fly Ash for Other General Applications

Agricultural fields

In agriculture, depending upon the characteristics of soil 50–650 t of fly ash per hectare of land can be utilized to improve the agricultural productivity. Most of the heavy metals/trace elements in Indian coal ash found in lower concentration than that of abroad, which is one of the advantages for utilisation in agriculture (Fig.5) and in embankment.

Com-pounds Pond ash Soils Compound Pond ash Soils

SiO2 37.7–75.1 43–61 MgO 0.1–0.8 0.2–3.0

Al2O3 11.7–53.3 12–39 CaO 0.2–0.6 0–7

TiO2 0.2–1.4 0.2–2 K2O 0.1–0.7 0.3–2

Fe2O3 3.5–34.6 1–14 Na2O 0.05–0.31 0.2–3

MnO bd–0.6 0–0.1 LOI 0.01–20.9 5–16

Table 3 Chemical Composition of Coal Ash and Soil

Figure 5 – Application of Fly Ash in Agriculture

Prospects of bulk use of Coal Ash in Agriculture

Fly Ash can be used as soil modifier in agriculture[Sudhir K Shrma et. al 2006]. The experiments on varied agro-climatic conditions and soil types on the cultivation of different field crops(fig.4) (cereals, pulses, oil seeds, sugar cane, vegetables, etc.) and forestry species with different doses of fly ash and pond ash as soil modifier / source of economical plant nutrients with respect to crop yield, soil health, quality of crop produce, uptake of nutrients and toxic heavy metals, ground water quality etc. have revealed the following:

- It improves permeability status of soil, fertility status of

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soil (soil health) / crop yield, soil texture, water holding capacity / porosity, soil aeration, sorption capacity.

- Reduces bulk density of soil, crust formation- Optimizes pH value- Provides micro nutrients like Fe, Zn, Cu, Mo, B, Mn, etc.

and macro nutrients like K, P, Ca, Mg, S etc

Active Role and Commitment of Organizations

Long term perspectives of coal ash management is deemed imperative and now it is necessary for the coal ash generators, scientists, technocrats, entrepreneurs, consumers along with decision/policy-makers to jointly put an effort for evolving a suitable paradigm for effective management of Coal Combustion Residues (CCRs) for the large scale utilization of Coal Ash followed by providing a multidisciplinary solution to cater the need and safe guard the environment [www.c-farm.org].

Few organizations which are involved actively to enhance the participation of all stakeholders and to help the government periodically in understanding the state of economics, technology, environmental and social aspects of coal production and usage are

- Department of Science and Technology - TIFAC – Technology Information Forecasting and

Assessment Council- Ministry of Environment and Forest - MOEF - Building Materials Technology and Promotion Council

and Housing and Urban Development Corporation - BMTPC,

- R&D work - Government of India have taken various initiatives and contributed not only for the financial and technical support to carryout R&D work but also for promoting of CCRs based building materials for large-scale production and utilisation.

- Provision in Indian Standard Codes of Practice – The Bureau of Indian standards, 3812:1981 and 456:2000 [Cl:5.2.1.1,pp13], has been revised to use coal combustion residues as pozzolana and admixture.

These objectives of core components of the National Action Plan on climate change, adding to the emphasis on efficiency and investment in renewable options. Clean energy is another key goal, but success here will depend on the effective implementation of few strategies made.

Regulation and Reforms

Recently, there has been a significant push towards reforming India’s coal sector (consistent with the broader trend of reforms and restructuring in various parts of the energy sector) and creating an independent regulator for coal and coal ash.

Ministry of environment and forests has issued following directions under section 3 & 5 of Environment (Protection) Act, 1986 vide a Gazette notification no. GSR . 763 (E) dated 14/09/1999 [User Manual , BMTPC 2012]

- Use of flyash, bottom ash or pond ash in the manufacture of bricks and other construction activities

- Utilisation of flyash by thermal power plants and- Specifications for use of flyash based products by

Government agencies

Present Status

Ash generation and utilization during 1st half of the year 2011 – 12 [Report CEB, New Delhi,2012].

A brief summary – Fly ash generation and utilization data for 1st half of the year 2012 – 11has been received from 90 coal / lignite based thermal power stations of various power utilities in the country with a total installed capacity of about 83797 MW. Data received has been analysed to derive conclusions on present status of fly ash utilization and compliance of MoEF Notification of 3rd Nov. 2009. A brief summary of status is given below[Report CEB, New Delhi,2012].

SL. No Details of Thermal Power Stations

1No. of Coal / Lignite based Thermal Power Stations from which data has

been received,90 No

2 Installed Capacity 83797 MV

3 Total Ash Generated 66.49 million tonne

4 Total Ash Utilised 36.26 million tonne

5 Percentage Utilisation 54.53%

Table 4 – Status of Thermal Power Stations [Report CEB, New Delhi,2012]

Trends / Attitudes

Most of the developments in the construction industry in the past have been in the direction of construction cost reduction, use of high tech (energy intensive) materials and faster construction through mechanization. Coal ash utilization in construction industry comes under use of energy intensive material, that reduces the cost of construction also.

Range of percentage ash utilization during the 1st Half of the Year 2011-12 [Report CEB, New Delhi,2012].

Power station wise fly ash generation and utilization data including mode of utilization for all the 90 thermal Power stations is given in the statement as Table - 7

Government Initiatives - Ministry of environment and forests has issued following directions under section 3 & 5 of Environment (Protection) Act, 1986 vide a Gazette notification no. GSR . 763 (E) dated 14/09/1999.

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- Use of fly ash, bottom ash or pond ash in the manufacture of bricks and other construction activities

- Utilisation of flyash by thermal power plants and Specifications for use of flyash based products by Government agencies

- Compulsory utilisation of fly ash in the all the type of constructions surrounding area of thermal power plants

operation after the date of notification should have achieved the target of 50% of fly ash utilization within one year of their commissioning.

Consumption of Fly Ash During the 1st Half of the Year 2011-12 [Report CEB, New Delhi,2012].

Sl. NoName of

Thermal Power Stations

Name of Power utilities

Fly ash utilization in Percentage

(1) (2) (3) (4)

1 Sabermati Torrent Power Limited 115.68

2 Mettur T.N.G.D.C.L 180.21

3 B.B.G.S C.E.S.C 100.00

Thermal Power Stations with ash Utilization Level of 100% or More During 1* Half of the year 2011-12Table – 6 Details of Number of TPS with percentage range of Ash utilization

Sl.No. Level of ash utilization Nos. of Power Stations

1 100% and more than 100% 16

2 Less than 100% and up to 75% 19

3 Less than 75% and up to 60% 14

4Less than 60% (for plants

commissioned before 3rd Nov. 2009)

39

5Less than 50% (for green field plants commissioned after 3rd

No.2009)2

Existing coal based power plants being monitored by the regulatory agencies and directions are issued to

- Use of beneficiated coal in thermal power plants- Emphasis on- Clean technology for new plants. - utilization of fly ash- Non-carbon/low carbon based technologies for power

sector and - Cogeneration

Present Status of Fly Ash utilization as Per Moef’s Amendment Notification Dated 3rd November, 2009

Fly ash generation and its utilization for 1ST half of the year 2011-12 (data received from various power utilities) for target of fly ash utilization as per MoEF’s notification of 3rd November, 2009

- All thermal power stations in operation on the date of notification should have achieved the target of 60% fly ash utilization within two years from the date of notification i.e. by 3rd November, 2011

- All new thermal power stations which have come into

Sl. NoMode of

utilization Utilization in (mt)Percentage utilization

(1) (2) (3) (4)

1 Cement 17.45 48.13

2Reclamation of low

lying area3.16 8.72

3Roads &

Embankments4.72 13.02

4 Mine filling 2.45 6.76

5 Bricks & Tiles 2.36 6.51

6 Agriculture 0.37 1.02

7 Others 5.74 15.83

Total 36.26 100

Thermal Power Stations with ash Utilization Level of 100% or More During 1* Half of the year 2011-12Table – 6 Details of Number of TPS with percentage range of Ash utilization

Table – 7 Details of Mode of Ash utilization in various fields

Presently 33% of the coal ash produced worldwide, finds market acceptability. In India, due to the incessant effort of R&D, today coal ash of more than 27% of total generation is being used in building materials including cement and concrete, road and embankment, land development and agriculture, extraction of metal and cenospheric ash, paints, waste treatment and hazardous waste management.

Hence effective utilization of coal ash as constituent in various constructions, a Green Infrastructure initiative, encourage

Fig.6 Details of Ash utilization in various fields

A pie diagram showing the modes of utilization of ash during 1st half of the year 2011 - 12 is given in Figure-1 below:

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- The large scale utilization of industrial waste- Facilitating human habitation, replacing fast depleting

natural resource - Contribute to sustainable construction and - Helps in conserving the precious top soil required for growing

food contributing to environmental and ecological benefits.

Conclusions

Greening the infrastructure is through adopting the practice of creating structures using materials / processes that are environmentally responsible and resource-efficient in every way possible, through the successful implementation of improved technologies (materials / methodology / ) that will reduce CO2 emissions and it is possible to reduce global warming.

Cities in developing nations can adopt best practices in urban planning and mobility management, as well as technological advances, to design sustainability into their new infrastructure. Every city is part of the solu¬tion.

Sustainable construction as published in ‘SUSTAINABILITY TOMORROW’ – July’07 – a quarterly brought out by the CIIITC, Centre for Excellence in Sustainable Development Sustainability in construction projects is generally achieved by

- Defining clear goals sympathetic to sustainability issues.

- Concentrated effort at design stage to achieve these goals.

- Choosing the right materials which are recyclable after their useful lives

- Choosing the right methods of construction in terms of energy and resource efficiency

- Creating an efficient and integrated building envelope harnessing the gifts of nature

This paper is one of the various initiatives and confidence building effort to spread the message of the responsibility of researchers, stake holders, all professionals in the field, towards conservation of natural resources and protection of environment. Now is the time to act!

“Fly Ash can become wealth generator. By making use of it for producing “green building” materials, roads, agriculture etc., Full utilization of the generating stock will provide employment potential for three hundred thousand people results in a business volume of Rs. 4000 crores”. – Excerpt from Indian past President A.P.J. Abdul Kalam’s address to the Nation on the eve of the country’s 56th Republic Day.

References

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